The present invention relates to an image sensing apparatus, focusing method, program, and storage medium, and more particularly, to an image sensing apparatus which always achieves a focused state by the hill-climbing focusing method, and before an actual image sensing operation, obtains a final focus position by re-driving (scanning) a lens in the vicinity of the focus position which has been achieved by the hill-climbing focusing method, a focusing method applied to said image sensing apparatus, a program which causes a computer to execute said focusing method, and a storage medium storing said program.
Conventionally, as a focusing method of an electronic still camera or a video camera or the like, the lens position of a focus lens is adjusted so as to achieve a maximum level of a high-frequency-range component, consisting only of luminance signals in a high-frequency range among the luminance signals for one frame obtained from an image sensing device, e.g., a CCD.
Known methods of this focusing method are: the hill-climbing method which obtains a focus position by driving a lens in the increasing direction of a level of a high-frequency-range component (hereinafter referred to as a xe2x80x9cfocus evaluation valuexe2x80x9d) among the luminance signals for one frame obtained from an image sensing device, and obtaining as the maximum value the focus evaluation value immediately before it decreases, and acquiring a lens position corresponding to the maximum value as the focus position; or a method which obtains a focus position by storing focus evaluation values for each of the lens positions in a predetermined focusing area while driving the lens, detecting the maximum value of the stored focus evaluation values after driving the lens across the whole driving areas, and acquiring a lens position corresponding to the maximum value as the focus position.
In these methods, normally the central area of an image sensing frame is designated as the predetermined focusing area as shown in FIG. 12, and a focus evaluation value within this area is obtained. FIG. 12 shows a focusing area of an image sensing frame. FIG. 13 shows a relation between lens positions and focus evaluation values in the predetermined focusing area. As can be seen in FIG. 13, the focus evaluation values form a mountain shape.
Furthermore, in a case of sensing a still image by an electronic still camera or a video camera, it is a known method to always achieve a focused state of an image in the electronic view finder by the aforementioned hill-climbing focusing method, and before an actual image sensing operation, re-drive (scan) the lens in the vicinity of the focus position which has been obtained by the hill-climbing focusing method to obtain a final focus position.
However, in the above-described image sensing apparatus employing the conventional method of re-driving (scanning) a lens in the vicinity of the focus position before an actual image sensing operation, for instance, in a case where the camera performs panning and then an actual image sensing operation has started before completing the hill-climbing focusing operation, the lens may scan the area that has the center different from the intended focus position, and may go but of focus.
The present invention has been proposed in consideration of the above-described problems, and has as its object to provide an image sensing apparatus, employing a method of obtaining a final focus position before an actual image sensing operation by re-driving a lens in the vicinity of a focus position which has been obtained by the hill-climbing focusing method, which enables to achieve accurate focusing even in a case where a focus position is not yet obtained by the hill-climbing focusing method, a focusing method, a program, and a storage medium.
In order to solve the above-described problems and achieve the object, a focus adjusting apparatus according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing a focus adjusting apparatus comprising: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation mode adapted to perform focus operation by storing signals extracted by the extraction unit at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control unit adapted to set a first range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed after completing the focus operation of the first focus operation mode, or set a second range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed before completing the focus operation of the first focus operation mode.
Furthermore, an image sensing apparatus according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing an image sensing apparatus comprising a focus adjusting apparatus which includes: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation mode adapted to perform focus operation by storing signals extracted by the extraction unit at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control unit adapted to set a first range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed after completing the focus operation of the first focus operation mode, or set a second range as the predetermined range of the second focus operation mode in a case where the second focus operation mode is executed before completing the focus operation of the first focus operation mode.
Furthermore, a focus adjusting apparatus according to the present invention is characterized by the following configuration according to its second aspect.
According to the present invention, the foregoing object is attained by providing a focus adjusting apparatus comprising: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation mode adapted to perform focus operation by storing signals extracted by the extraction unit at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control unit adapted to set a first range as the predetermined range of the second focus operation mode in a case where the focus level obtained in the first focus operation mode is higher than a predetermined value, or set a second range as the predetermined range of the second focus operation mode in a case where the focus level obtained in the first focus operation mode is equal to or lower than the predetermined value.
Furthermore, an image sensing apparatus according to the present invention is characterized by the following configuration according to its second aspect.
According to the present invention, the foregoing object is attained by providing an image sensing apparatus comprising a focus adjusting apparatus which includes: an extraction unit adapted to receive object light through a focus lens that performs focus adjustment, and extract a signal indicative of a focus level; a first focus operation mode adapted to perform focus operation by moving the focus lens while determining a focus level based on the signal extracted by the extraction unit, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation mode adapted to perform focus operation by storing signals extracted by the extraction unit at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control unit adapted to set a first range as the predetermined range of the second focus operation mode in a case where the focus level obtained in the first focus operation mode is higher than a predetermined value, or set a second range as the predetermined range of the second focus operation mode in a case where the focus level obtained in the first focus operation mode is equal to or lower than the predetermined value.
Furthermore, a focusing method according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing a focusing method comprising: an extraction step of receiving object light through a focus lens that performs focus adjustment and extracting a signal indicative of a focus level; a first focus operation step of performing focus operation by moving the focus lens while determining a focus level based on the signal extracted in the extraction step, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation step of performing focus operation by storing signals extracted in the extraction step at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control step of setting a first range as the predetermined range of the second focus operation step in a case where the second focus operation step is executed after completing the focus operation of the first focus operation step, or setting a second range as the predetermined range of the second focus operation step in a case where the second focus operation step is executed before completing the focus operation of the first focus operation step.
Furthermore, a focusing method according to the present invention is characterized by the following configuration according to its second aspect.
According to the present invention, the foregoing object is attained by providing a focusing method comprising: an extraction step of receiving object light through a focus lens that performs focus adjustment and extracting a signal indicative of a focus level; a first focus operation step of performing focus operation by moving the focus lens while determining a focus level based on the signal extracted in the extraction step, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation step of performing focus operation by storing signals extracted in the extraction step at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control step of setting a first range as the predetermined range of the second focus operation step in a case where the focus level obtained in the first focus operation step is higher than a predetermined value, or setting a second range as the predetermined range of the second focus operation step in a case where the focus level obtained in the first focus operation step is equal to or lower than the predetermined value.
Furthermore, a program according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing a program which causes a computer to execute steps including: an extraction step of receiving object light through a focus lens that performs focus adjustment and extracting a signal indicative of a focus level; a first focus operation step of performing focus operation by moving the focus lens while determining a focus level based on the signal extracted in the extraction step, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation step of performing focus operation by storing signals extracted in the extraction step at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control step of setting a first range as the predetermined range of the second focus operation step in a case where the second focus operation step is executed after completing the focus operation of the first focus operation step, or setting a second range as the predetermined range of the second focus operation step in a case where the second focus operation step is executed before completing the focus operation of the first focus operation step.
Furthermore, a program according to the present invention is characterized by the following configuration according to its second aspect.
According to the present invention, the foregoing object is attained by providing a program which causes a computer to execute steps including: an extraction step of receiving object light through a focus lens that performs focus adjustment and extracting a signal indicative of a focus level; a first focus operation step of performing focus operation by moving the focus lens while determining a focus level based on the signal extracted in the extraction step, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation step of performing focus operation by storing signals extracted in the extraction step at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control step of setting a first range as the predetermined range of the second focus operation step in a case where the focus level obtained in the first focus operation step is higher than a predetermined value, or setting a second range as the predetermined range of the second focus operation step in a case where the focus level obtained in the first focus operation step is equal to or lower than the predetermined value.
Furthermore, a storage medium according to the present invention is characterized by the following configuration according to its first aspect.
According to the present invention, the foregoing object is attained by providing a storage medium readable by a computer, the medium storing a program realizing: an extraction step of receiving object light through a focus lens that performs focus adjustment and extracting a signal indicative of a focus level; a first focus operation step of performing focus operation by moving the focus lens while determining a focus level based on the signal extracted in the extraction step, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation step of performing focus operation by storing signals extracted in the extraction step at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control step of setting a first range as the predetermined range of the second focus operation step in a case where the second focus operation step is executed after completing the focus operation of the first focus operation step, or setting a second range as the predetermined range of the second focus operation step in a case where the second focus operation step is executed before completing the focus operation of the first focus operation step.
Furthermore, a storage medium according to the present invention is characterized by the following configuration according to its second aspect.
According to the present invention, a storage medium readable by a computer, the medium storing a program realizing: an extraction step of receiving object light through a focus lens that performs focus adjustment and extracting a signal indicative of a focus level; a first focus operation step of performing focus operation by moving the focus lens while determining a focus level based on the signal extracted in the extraction step, and when it is determined that the focus lens has passed a position where the focus level becomes maximum, returning and stopping the focus lens at the position where the focus level becomes maximum; a second focus operation step of performing focus operation by storing signals extracted in the extraction step at each of a plurality of positions of the focus lens while moving the focus lens across a predetermined range in response to an operation of a shutter release operation member, and moving the focus lens to a position where the focus level becomes maximum in the stored signals; and a control step of setting a first range as the predetermined range of the second focus operation step in a case where the focus level obtained in the first focus operation step is higher than a predetermined value, or setting a second range as the predetermined range of the second focus operation step in a case where the focus level obtained in the first focus operation step is equal to or lower than the predetermined value.
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part thereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.